Construction of coupling exhaust pipes of vehicle

ABSTRACT

An opening edge of an upstream-side exhaust pipe and an opening edge of a downstream-side exhaust pipe opposed to the opening edge of the upstream-side exhaust pipe are bent radially outward and thereafter radially inward by molding to form a circumference of the upstream-side exhaust pipe and a circumference of the downstream-side exhaust pipe as a flange portion respectively. After both flange portions are butted to each other through a gasket disposed therebetween, they are mechanically coupled to each other with a bolt and a nut.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a construction of coupling exhaust pipes of a vehicle to each other and more particularly to a coupling construction, having a smaller number of parts, which is capable of coupling exhaust pipes to each other without welding the exhaust pipes to each other.

2. Description of the Related Art

FIGS. 11 and 12 show an example of conventional constructions of coupling exhaust pipes to each other. With reference to FIG. 12, approximately rhombic (see FIG. 11) coupling flanges 61 and 62 are welded to the periphery of an end of an upstream-side exhaust pipe 1 and that of a downstream-side exhaust pipe 2 respectively. The upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 are coupled to each other by coupling the coupling flanges 61 and 62 to each other with a bolt 64 and a nut 65 through a gasket 63 disposed between the coupling flanges 61 and 62 (first conventional example).

FIGS. 13 and 14 show another example of the conventional constructions of coupling exhaust pipes. With reference to FIG. 14, one side of locking rings 71, 72 formed in a shape similar to a letter “V” in section is welded to the entire periphery of an end of an upstream-side exhaust pipe 1 and that of a downstream-side exhaust pipe 2 respectively. The upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 are coupled to each other by fitting a pair of sandwiching bands 74, 75 on the locking rings 71, 72 respectively, with a ring-shaped packing 73 interposed between the other side of the locking ring 71 and the other side of the locking ring 72 disposed symmetrically with respect to the locking ring 71. Each of the sandwiching bands 74, 75 is formed by shaping a belt-shaped plate into a semicircle mountain-shaped in section (see FIG. 13). One end of the sandwiching band 74 and that of the sandwiching band 75 are rotatably locked to each other. After the sandwiching bands 74, 75 are fitted on the locking rings 71, 72 respectively, the other ends of the sandwiching bands 74, 75 are coupled to each other with a bolt 76 and a nut 77 (second conventional example).

In the construction of coupling exhaust pipes to each other disclosed in Japanese Patent Application Laid-Open No. 2002-227643, after the clamping fitting is mounted on one of the exhaust pipes, and another clamping fitting is mounted on the other exhaust pipe fitted in the one exhaust pipe, both exhaust pipes are coupled to each other by tightening the clamping fittings with a bolt and a nut.

In the above-described conventional constructions of coupling exhaust pipes to each other, it is necessary to weld the coupling flanges 61, 62 of the first conventional example to the periphery of the end of the exhaust pipes 1, 2 respectively. It is also necessary to weld the locking rings 71, 72 of the second conventional example to the periphery of the end of the exhaust pipes 1, 2 respectively. Therefore each of the above-described constructions has a problem that a stress concentrates on the welded portion and thus the exhaust pipes 1, 2 are liable to crack owing to vibrations of a vehicle body and that time and labor are required in a welding process. The first conventional example has another problem that when a face pressure is increased to prevent leak of a gas from the gasket 63, it is necessary to set the thickness of the coupling flanges 61 and 62 to as thick as 10 to 12 mm. Hence the weight and cost of the coupling construction increase. The second conventional example has another problem that many component parts are used for the coupling construction.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above-described problems. Therefore it is an object of the present invention to provide a construction of coupling exhaust pipes of a vehicle which does not have a possibility of breakage, even though the vehicle body vibrates, does not cause an increase in the weight and cost thereof, and in the number of component parts, and can be manufactured easily.

To achieve the above-described object, in the first invention, in a construction of coupling exhaust pipes of a vehicle, an opening edge of an upstream-side exhaust pipe and an opening edge of a downstream-side exhaust pipe opposed to the opening edge of the upstream-side exhaust pipe are bent radially outward to form a circumference of the upstream-side exhaust pipe and a circumference of the downstream-side exhaust pipe as a flange portion respectively; and after the both flange portions are butted to each other through a sealing member disposed between the both flange portions, the both flange portions are mechanically coupled to each other by means of coupling members.

In the first invention, the coupling construction does not have a portion to be welded unlike the conventional coupling construction. Further the coupling construction can be prevented from cracking because a stress does not concentrate on a welded portion. In addition, time and labor can be saved because it is unnecessary to perform a welding process. Further because it is unnecessary to use thick coupling flanges to obtain a face pressure necessary for preventing leak of gas, it is possible to prevent an increase in the weight of the coupling construction and the cost thereof. Furthermore because the flange portions are formed by bending the opening edge of the upstream-side exhaust pipe and that of the downstream-side exhaust pipe, it is possible to use a smaller number of parts for the coupling construction of the present invention than for the conventional coupling construction in which the coupling flanges are welded to the upstream-side exhaust pipe and the downstream-side exhaust pipe respectively.

In the second invention, in a construction of coupling exhaust pipes of a vehicle, an opening edge of an upstream-side exhaust pipe and an opening edge of a downstream-side exhaust pipe opposed to the opening edge of the upstream-side exhaust pipe are bent radially outward to form a circumference of the upstream-side exhaust pipe and a circumference of the downstream-side exhaust pipe as a flange portion respectively; and after the both flange portions are butted to each other through a sealing member disposed between the both flange portions, the both flange portions are coupled to each other by means of a pair of sandwiching members which sandwiches the both flange portions therebetween at an outer side of each of the flange portions in a direction in which the both opening edges are opposed to each other. The second invention provides an effect similar to that of the first embodiment.

In the third invention, a flange portion is formed by crushing in a longitudinal direction of a pipe at least one of adjacent bulged portions formed by bulging the pipe radially outward at an intermediate position of the pipe spaced at a predetermined interval from an opening of the pipe in such a way as to superimpose both slopes of each of the sectionally mountain-shaped bulged portions each other. In the third invention, the pipe at the intermediate position thereof spaced at the predetermined interval from the opening is projected. Therefore the wall of the pipe between the opening and the base of the mountain at the side of the opening is supplied to the bulged portion owing to the increase of the diameter of the intermediate position of the pipe. Thus it is possible to prevent the thickness of the bulged portion from becoming excessively thin. Consequently it is possible to shape the bulged portion and the flange portion, with the bulged portion and the flange portion keeping a sufficient thickness.

As apparent from the foregoing description, the construction of coupling exhaust pipes of a vehicle does not have a fear of breakage even though a vehicle body vibrates, does not cause an increase in the weight and cost thereof, and the number of component parts, and can be manufactured easily.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing coupled exhaust pipes of a vehicle in a first embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along a line II-II of FIG. 1.

FIG. 3 is a vertical sectional view taken along a line III-III of FIG. 1.

FIG. 4 is across-sectional view showing coupled exhaust pipes of a vehicle in a second embodiment of the present invention.

FIG. 5 is a vertical sectional view taken along a line V-V of FIG. 4.

FIG. 6 is a vertical sectional view taken along a line VI-VI of FIG. 4.

FIG. 7 is a sectional view showing a process of manufacturing a flange portion in a third embodiment of the present invention.

FIG. 8 is a sectional view showing a process of manufacturing a flange portion in a fourth embodiment of the present invention.

FIG. 9 is a perspective view and a sectional view showing a process of manufacturing a flange portion in a fifth embodiment of the present invention.

FIG. 10 is a perspective view and a sectional view showing a process of manufacturing a flange portion in a sixth embodiment of the present invention.

FIG. 11 is a cross-sectional view showing exhaust pipes of a vehicle coupled to each other with a conventional coupling construction.

FIG. 12 is a vertical sectional view taken along a line XII-XII of FIG. 11.

FIG. 13 is a cross-sectional view showing exhaust pipes of a vehicle coupled to each other with another conventional coupling construction.

FIG. 14 is a vertical sectional view taken along a line XIV-XIV of FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIGS. 1 through 3 show an example of the coupling construction of the present invention. FIG. 1 is a cross-sectional view showing coupled exhaust pipes of a vehicle. FIGS. 2 and 3 are a vertical sectional view taken along a line II-II of FIG. 1 and a line III-III of FIG. 1 respectively. As shown in FIGS. 2 and 3, an upstream-side exhaust pipe 1 and a downstream-side exhaust pipe 2 are disposed at predetermined positions, with edges 11 and 21 of openings thereof opposed to each other. Each of the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 has a thickness of 1.2 to 1.5 mm. The edges 11, 21 of the openings of the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 are bent radially outward by molding and thereafter folded back radially inward to form flange portions 12 and 22 having a predetermined width on the circumference of each of the openings respectively. The flange portions 12, 22 are butted to each other through a gasket 31 disposed therebetween and coupled to each other with a bolt 41 and a nut 42 at radially symmetrical positions (see FIG. 1). The upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 are coupled to each other in this manner. The peripheral edges of the flange portions 12, 22 are bent substantially perpendicularly (see FIG. 3) at a height of 7 to 8 mm except bolt-penetrated portions of the flange portions 12, 22 to form the peripheral edges thereof as reinforcing ribs 13, 23 respectively. Thereby the face pressure of the gasket 31 is securely obtained.

In the first embodiment, the coupling construction does not have a portion to be welded unlike the conventional coupling construction. Further the coupling construction can be prevented from cracking because a stress does not concentrate on a welded portion. In addition, time and labor can be saved because it is unnecessary to perform a welding process. Further because it is unnecessary to use thick coupling flanges to obtain a face pressure necessary for preventing leak of gas, it is possible to prevent an increase in the weight of the coupling construction and the cost thereof. Furthermore because the flange portions 12, 22 are formed by bending the opening edges 11, 21 of the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 respectively, it is possible to use a smaller number of parts for the coupling construction of the present invention than for the conventional coupling construction in which the coupling flanges 61, 62 (see FIG. 12) are welded to the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 respectively.

Second Embodiment

FIGS. 4 through 6 show another example of the coupling construction of the present invention. FIG. 4 is a cross-sectional view showing coupled exhaust pipes of a vehicle. FIGS. 5 and 6 are a vertical sectional view taken along a line V-V of FIG. 4 and a line VI-VI of FIG. 4 respectively. In the second embodiment, an upstream-side exhaust pipe 1 and a downstream-side exhaust pipe 2 are disposed at predetermined positions, with edges 11 and 21 of openings thereof opposed to each other. Each of the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 has a thickness of 1.2 to 1.5 mm. The edges 11, 21 of the openings of the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 are bent radially outward by molding and thereafter folded back radially inward to form flange portions 14 and 24 having a predetermined width on the circumference of each of the openings thereof respectively. The flange portions 14 and 24 are butted to each other through a large-diameter gasket 32 disposed therebetween. A peripheral portion of the gasket 32 projects radially outward beyond the periphery of the flange portions 14 and 24. Sandwiching rings 5A, 5B movably fitted on the periphery of the upstream exhaust pipe 1 and the downstream exhaust pipe 2 contact the half of the peripheral portion of the gasket 32 respectively. It is possible to make the width of the flange portions 14, 24 of the second embodiment smaller than that of the flange portions 12, 22 of the first embodiment. Therefore it is possible to reduce burden in a molding operation.

Inner peripheral portions 51 of the sandwiching rings 5A, 5B are sectionally curvedly disposed along outer surfaces of the flange portions 14, 24 in the direction in which the flange portions 14, 24 of the upstream exhaust pipe 1 and the downstream exhaust pipe 2 are opposed to each other, with the inner peripheral portions 51 of the sandwiching rings 5A, 5B in contact with the outer surfaces of the flange portions 14, 24. The peripheral portions of the sandwiching rings 5A, 5B are opposed to each other, with the gasket 32 sandwiched therebetween. The sandwiching rings 5A, 5B are coupled to each other at symmetrical positions (see FIG. 4), with bolts 41 and nuts 42. In this manner, the upstream exhaust pipe 1 and the downstream exhaust pipe 2 are coupled to each other. The peripheral edges of the sandwiching rings 5A, 5B are bent substantially perpendicularly (see FIG. 6) at a height of 7 to 8 mm except bolt-penetrated portions thereof to form the peripheral edges thereof as reinforcing ribs 52, 52 respectively. Thereby the face pressure of the gasket 31 is securely obtained.

The coupling construction of the second embodiment does not have a portion to be welded unlike the conventional coupling construction. Further the coupling construction can be prevented from cracking because a stress does not concentrate on a welded portion. In addition, time and labor can be saved because it is unnecessary to perform a welding process. Further because thick coupling flanges are not required to obtain a face pressure necessary for preventing leak of gas, it is possible to prevent an increase in the weight of the coupling construction and the cost thereof. Furthermore because the flange portions 14, 24 are formed by bending the edges 11, 21 of the openings of the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 respectively, it is possible to use a smaller number of parts for the coupling construction of the present invention than for the conventional coupling construction in which the coupling flanges 71, 72 (see FIG. 14) are welded to the upstream-side exhaust pipe 1 and the downstream-side exhaust pipe 2 respectively.

Third Embodiment

FIG. 7 shows another method of forming a flange portion on the circumference of an opening of an exhaust pipe. With the peripheral portion of a pipe 8 shown with triangles of FIG. 7(1) clamped by an appropriate means, the diameter of the pipe 8 at an intermediate position thereof spaced at a predetermined interval from an opening 81 is increased so that the intermediate portion of the pipe 8 is mountain-shaped in section by beading processing. Thereby a bulged portion 82 is formed on the pipe 8. The triangles in each of the following embodiments show the peripheral portion of the pipe clamped by an appropriate means. Because the diameter of the pipe 8 at the intermediate position thereof spaced at the predetermined interval from the opening 81 is increased, the wall of the pipe 8 between the opening 81 and the base of the mountain at the side of the opening 81 is supplied to the bulged portion 82 owing to the increase of the diameter of the intermediate position of the pipe 8. Thus it is possible to prevent the thickness of the bulged portion 82 from becoming excessively thin. Thereafter the pipe 8 is cut at the position of the base of the sectionally mountain-shaped bulged portion 82 at the side of the opening 81 to form an opening 83 (see FIG. 7(2)). Thereafter a slope 821 at the side of the opening 83 with respect to the apex of the sectionally mountain-shaped bulged portion 82 is crushingly pressed against a slope 822 disposed at the other side by means of press molding (see FIG. 7(3)). Thereby a flange portions 84 is formed erectly on the circumference of the opening 83.

Fourth Embodiment

FIG. 8 shows still another method of forming a flange portion on the circumference of an opening of an exhaust pipe. With the peripheral portion of a pipe 8 shown with triangles of FIG. 8(1) clamped by an appropriate means, a plurality of punches PT are inserted into an intermediate position inside the pipe 8 spaced at a predetermined interval from an opening 81. That is, the diameter of the pipe 8 at the intermediate position inside the pipe 8 is increased so that the intermediate portion of the pipe 8 is approximately mountain-shaped in section. Thereby a bulged portion 82 is formed on the pipe 8. Thereafter the pipe 8 is cut at the position of the base of the sectionally mountain-shaped bulged portion 82 at the side of the opening 81 to form an opening 83 (see FIG. 8(2)). Thereafter a slope 821 at the side of the opening 83 with respect to the apex of the sectionally mountain-shaped bulged portion 82 is crushingly pressed against a slope 822 disposed at the other side by means of press molding (see FIG. 8(3)). Thereby a flange portions 84 is formed erectly on the circumference of the opening 83. The method of the fourth embodiment is also capable of preventing the bulged portion 82 from becoming excessively thin like the method of the third embodiment. The bulged portion 82 may be formed by a hydraulic bulging processing.

Fifth Embodiment

FIG. 9 shows still another method of forming a flange portion on the circumference of an opening of an exhaust pipe. Initially as shown in FIG. 9(1), a metal plate 10 is formed into the shape of an approximately U in section by press working. At this time, the metal plate 10 is deformed outward at an intermediate position thereof spaced at a predetermined interval from one end surface 101 so that an intermediate portion is approximately mountain-shaped in section to form a bulged portion 92. After the metal plate 10 is shaped cylindrically by press molding (see FIG. 9(2)), butted ends 923 of the metal plate 10 extending in the longitudinal direction thereof are welded to each other to form a pipe 9 having the bulged portion 92 disposed at an intermediate position spaced at a predetermined interval from an opening 91. Stray current corrosion does not take place in the welding in this case, because metals to be welded are of the same kind. Thereafter the pipe 9 is cut at the base of the sectionally mountain-shaped bulged portion 92 at the side of the opening 91 thereof to form an opening 93 (see FIG. 9(3)). A slope 921 at the side of the opening 93 with respect to the apex of the sectionally mountain-shaped bulged portion 92 is crushingly pressed against a slope 922 disposed at the other side by means of press molding (see FIG. 9(4)). Thereby a flange portions 94 is formed erectly on the circumference of the opening 93. The fifth embodiment is suitable for manufacturing a flange portion-provided exhaust pipe having a large diameter.

Sixth Embodiment

FIG. 10 shows still another method of forming a flange portion on the circumference of an opening of an exhaust pipe. As shown in FIG. 10(1), a metal plate 10 is formed into the shape of an approximately U in section by press working. At this time, the metal plate 10 is deformed bulgingly outward at intermediate two positions, longitudinally adjacent to each other, which are spaced at a predetermined interval respectively from one end surface 101 so that the intermediate position is approximately mountain-shaped in section to form bulged portions 92A, 92B. After the metal plate 10 is shaped cylindrically by press molding (see FIG. 10(2)), butted ends 923 of the metal plate 10 extending in the longitudinal direction thereof are welded to each other to form a pipe 9 having the bulged portions 92A, 92B located at positions spaced at a predetermined interval respectively from an opening 91. Thereafter the pipe 9 is cut at the base of the sectionally mountain-shaped bulged portion 92A at the side of the opening 91 thereof to form an opening 93 (see FIG. 10(3)). Slopes 921 at the side of the opening 93 with respect to the apex of the sectionally mountain-shaped bulged portions 92A, 92B are crushingly pressed against slopes 922 disposed at the other side with respect to the apex of the bulged portions 92A, 92B by means of press molding (see FIG. 10(4)). Thereby a flange portion 94 is formed erectly on the circumference of the opening 93. The method of the sixth embodiment is suitable for manufacturing a flange portion-provided exhaust pipe having a large diameter and allows the flange portion 94 to have a large thickness. When a flange is formed by forming not less than three bulged portions and by crushing pressing bulged portions against slopes, the flange portion is allowed to have a large thickness.

Other Embodiments

In each of the above-described embodiments, when the flange portions 12, 22 have a sufficient strength, it is unnecessary to bend the edges of the exhaust pipes radially inward or form the reinforcing ribs 13, 23. Further when the sandwiching rings 5A, 5B have a sufficient strength, it is unnecessary to form the reinforcing ribs 52. 

1. A construction of coupling exhaust pipes of a vehicle, wherein an opening edge of an upstream-side exhaust pipe and an opening edge of a downstream-side exhaust pipe opposed to said opening edge of said upstream-side exhaust pipe are bent radially outward to form a circumference of said upstream-side exhaust pipe and a circumference of said downstream-side exhaust pipe as a flange portion respectively; and in the state of said both flange portions are butted to each other through a sealing member disposed between said both flange portions, said both flange portions are mechanically coupled to each other by means of coupling members.
 2. A construction of coupling exhaust pipes of a vehicle, wherein an opening edge of an upstream-side exhaust pipe and an opening edge of a downstream-side exhaust pipe opposed to said opening edge of said upstream-side exhaust pipe are bent radially outward to form a circumference of said upstream-side exhaust pipe and a circumference of said downstream-side exhaust pipe as a flange portion respectively; and after said both flange portions are butted to each other through a sealing member disposed between said both flange portions, said both flange portions are coupled to each other by means of a pair of sandwiching members which sandwiches said both flange portions therebetween at an outer side of each of said flange portions in a direction in which said both opening edges are opposed to each other.
 3. A construction of coupling exhaust pipes of a vehicle according to claim 1, wherein said flange portion is molded radially outward by bending said edges of said openings and radially inward at least once.
 4. A construction of coupling exhaust pipes of a vehicle according to claim 3, wherein said flange portion is formed by crushing in a longitudinal direction of a pipe at least one of adjacent bulged portions formed by bulging said pipe radially outward at an intermediate position of said pipe spaced at a predetermined interval from an opening of said pipe in such a way as to superimpose both slopes of each of said sectionally mountain-shaped bulged portions each other.
 5. A construction of coupling exhaust pipes of a vehicle according to claim 2, wherein said flange portion is molded radially outward by bending said edges of said openings and radially inward at least once. 